In a wireless multiple access communication system, wireless terminals contend for system resources in order to communicate with a common receiver over an uplink channel. An example of this situation is the uplink channel in a cellular wireless system, in which wireless terminals transmit to a base station receiver. When a wireless terminal transmits on the uplink channel, it typically causes interference to the entire system, e.g., neighboring base station receivers. Since wireless terminals are distributed, controlling the interference generated by their transmission is a challenging problem.
Many cellular wireless systems adopt simple strategies to control uplink interference. For example CDMA voice systems (e.g., IS-95) power control wireless terminals in such a manner that their signals are received at the base station receiver at approximately the same power. State-of-the-art CDMA systems such as 1xRTT and 12xEV-DO allow to wireless terminals to transmit at different rates, and be received at the base station at different powers. However, interference is controlled in a distributed manner which lowers the overall level of interference without precisely controlling those wireless terminals that are the worst sources of interference in the system.
Existing interference-control approaches can be useful but interference continues to limit the uplink capacity of wireless systems and new and/or improved interference control methods would be useful.
It would be useful if a base station could be provided with information that could be used in determining the amount of signal interference that will be created in neighboring cells and/or sectors when a transmission occurs and/or determining the amount of interference a wireless terminal is likely to encounter due to signal interference. It would be particularly desirable if information which can be used for interference determination purposes could be supplied by one or more wireless terminals to a base station.
Loading affects interference considerations in a wireless communications system. It would be beneficial if in some, but not necessarily all implementations, such information was available to wireless terminals and/or base stations. It could also be beneficial if wireless terminals and/or base stations were to utilize such loading information in determining interference levels. Accordingly, there is a need for new methods and/or apparatus for communicating and/or using loading interference information for interference control purposes.
A wireless terminal currently connected and synchronized with respect to one base station attachment point may be readably able to receive detailed characteristic information being broadcast from the base station to which it has a current connection; however, the wireless terminal may have difficulty recovering information from other, e.g., adjacent base stations. If a wireless terminal could be expected to be able to recover loading information about the base stations in its vicinity, such information could be used in a well controlled interference report. It would be beneficial if methods and apparatus facilitated the reliable delivery to such a wireless terminal of loading information from a plurality of base stations in its current vicinity.
Some communications systems may use a centralized control approach, e.g., using a core node, to manage interference and/or load balance; however, such an approach is subject to signaling and processing delays, and may limit the amount of information that can be reasonably communicated to the core node. Thus a core node approach used in some systems may tend to be sluggish or unable to quickly adapt to changing conditions resulting in efficient allocation resources.
In view of the above discussion, it should be appreciated that there is a need for improvements in communication of information which can be used in controlling interference and/or new and improved interference management techniques.